Controllable limit means for regulating strokes of fluid pressure apparatus



F. JIRSA CONTROLLABLE LIMIT MEANS FOR REGULATING March 2, 1954 STROKES OF FLUID PRESSURE APPARATUS 2 Sheets-Sheet 1 Filed Oct. 6, 1948 FIG. I

INVEN TOR E. F'. J/RSA ATTORNEYS March 2, 1954 sA 2,670,713

CONTROLLABLE LIMIT MEANS FOR REGULATING STROKES OF FLUID PRESSURE APPARATUS Filed Oct. 6, 1948 2 Sheets-Sheet 2 Patented Mar. 2, 1954 CONTROLLABLE LIMIT MEANS FOR REGU- LATING STROKES OF FLUID PRESSURE APPARATUS Emil F. Jirsa, Waterloo, Iowa, assignor to Deere Manufacturing 00., Dubuque, Iowa, a corporation of Iowa Application October 6, 1948, Serial No. 53,066

8 Claims.

This invention relates to fluid-pressure apparatus and particularly to means for regulating or controlling the stroke of a fluid-pressure motor.

Although the principles of the invention are capable of application in many and divers fields, the preferred form of the invention to be detailed subsequently herein was designed primarily for utilization in the regulation or control of agricultural implements of that class comprising a vehicle or equivalent supporting frame having a source of power for driving a fluid-pressure pump or the like to supply fluid under pressure to a motor, such as a cylinder and piston assembly, which is in turn connected to an adjustable implement part, such as a plow or earthworking tool or the platform of a harvester or equivalent machine. In the cas of a plow, for example, it is desirable to adjust the plow so that it will plow at a uniform depth. It is further desirable that the plow may be raised from its plowing or working position, as at the end of a furrow, and be readily returned to Working position by lowering of the same to the selected uniform depth, as when beginning a new furrow.

In one particular system, this general result is efiiciently and simply achieved by the use of a pair of cooperating stops or abutment members on the relatively movable motor parts, such as the cylinder and piston. The fluid-pressure system is provided with a relief valve which operates in response to an excess of pressure in the system to return a main control valve to neutral to discontinue the supply of fluid to the motor or the exhaust of fluid from the motor. cooperating stops may be adjusted in accordance with the desired position of adjustment of'the implement part, so that when th implement part reaches its desired position, one stop Will engage the other and prevent further relative movement of the motor parts, bringing about a condition of excess pressure which will affect the main control valve to isolate the motor from the fluid-pressure source. A disadvantage noted in this system is that the stops are positive in action and the motor cannot b operated to adjust the implement part beyond the position selected; that is to say, the plow, for example, having once had its position determined by the cooperating stops, cannot b moved to a greater depth Without a readjustment of the stops. In the case of a plow or analogous equipment, the

implement part or equivalent adjustable part is remotely located with respect to the fluid-pressure source,since the latter is on the tractor or These propelling vehicle and the adjustable part is connected behind the tractor, for example, on trailing supporting structure. Therefore, it is necessary in the system referred to above for the operator to dismount from the tractor to accomplish a readjustment of the cooperating stops.

According to the present invention, the above system is modified and improved to the extent that stop means is effective to accomplish a limit on the amount of relative movement of the motor part for the general purposes stated above. The cooperating parts of the stop means are adjustable so that any desired normal limit may be effected. However, the stop means further includes provision for additional movement beyond the range of movement of the motor parts determined by the original setting of the stops. This object is preferably achieved in a system in which the fluid-pressure apparatus has a main control valve capable of regulating the volume of fluid supplied to the motor so that the motor may be caused to operate at either a high or a low speed;

The control valve has, of course, a neutral position in which the motor is isolated from the fluid-pressure source. The system further preferably includes a pressure-relief valve effective to return the control valve to its neutral position in response to any condition of excess pressure in the system. In operation, the stop means is set in a desired position of adjustment and the normal adjusted position of the implement is effected after predetermined relative movement of the motor parts, the system operating like that previously described to the extent that a condition of excess pressure is created to cause the main control valve to return to neutral. In the present case, however, should the operator desire to move the implement beyond its normal adjusted position, he may operate the system at low speed, an important feature of the invention residing in the provision of a valve in'the stop means which has a throttling or by-pass means which establishes a restriction to operation of the system at high speed but which will permit operation of the system at low speed.

An important object of the invention is to adapt the general idea discussed above to a fluidpressure system of an existing type. In this respect, it is an object of the invention to incorporate the stop means and valve as part of a conventional or standard fluid-pressure motor of the cylinder-piston type. Generally, the invention contemplates the provision of a simplified and easily controlled fluid-pressure system.

The foregoing and other important objects and 3 desirable features inherent in and encompassed by the present invention will become apparent to those versed in the art as a preferred form of the invention is fully described and illustrated in the following detailed description and accompanying sheets ofdrawings in which:

Figure l is a representative illustration of an implement arrangement to which the improvedsystem may be applied;

Figure 2 is an enlarged sectional? view-,somewhat schematic, of that portion of the: fluidpressure apparatus including the source of fluid pressure, the pressure-relief valve, and the main.

control valve;

Figure 3 is an enlarged side elevational View, partly in section, of the fluid-pressure motor as incorporating the improved stop means; and- Figure 4 is a plan view, partly in section, of the arrangement shown in Figure 3.

The representative structure chosen for the purposes of illustration comprises, as shown in Figure 1, a tractor and a trailing implement. The tractor may be of any conventional construction and includes a longitudinal main body Ill carried on rear traction wheels H and provided' with a rearwardly disposed'operators station IZ'ahead of which is located an engine hood structure I3 within which is enclosed the usual power plant (not shown) for supplying power to the traction wheels I l.

The particular implement shown by way of illustration is a plow having a main frame I4 provided'with a cranked axle 45 on which is journaleda. ground wheel :6. The forward end of the frame [4 includes a draft member 11 which is pivotally connected at l3 to a conventional drawb'a'r Won the tractor body iii, The groundwiprking. toolv is here represented by a plow bottom 2 L The plow frame or. supporting structure is is provided just above the wheel 58 with a bearing ZI' on. which is pivoted a bell. crank having first andsecond'arms 22' and 23; The free end of the arm. 22 is connected by a link 28 to the cranked axl'ei l; Rocking of the bell crank 22'23' in a clockwise direction, as viewed in Figure 1, will apply pressure through the link 24 to the axle l5 and will effect raising of the implement part comprising the frame i l and plow bottom The parts are shown in Figure 1 in substantially their uppermost positions. Rocking of the bell crank, in a counterclockwise direction will result ina lowering of the parts 14 and 23. It will be understood that the connection of the hitch I! to theframe I4 is accomplished in such manner as to provide for the necessary articulation of the frame 14 with respect to the hitch member H, as by a pivot at 25. The general structure and arrangement of the tractor and implement are or may be conventional and resort need not be hadto further detailed description thereof.

Adjustment of the plow bottom 23 between its raised position as shown and a lowered or groundworking position is accomplished by fluid-pressure apparatus comprising a fluid motor 2%; means for controlling the supply of fluid under pressure to the motor, designated generally by the numeral 27 in Figure 1'; and a fluid-pressure circuit including the components 26 and 2? and a pairof conduits 28 and 29.

The motor 26 comprises a cylinder Siland a piston 3| (Figure 3). The cylinder 3c" forms a chamber within which the piston 3! is reciprocable and the latter includes a piston rod 32 having at its freeenda clevis 33 for attachment at 4 34 to the upper end of the bell crank arm 23. The closed end of the cylinder 38 has a clevis 35 connected at 36 to an upturned supporting portion 31 at the forward end of the implement frame l4. It will be seen that extension of the piston andlpiston rod with respeciito the cylinder 36 will rock the bell crank 22-23ii1 a clockwise direction to raise the plow bottom and frame, and that retraction of the piston and piston rod will rock the bell crank in a counterclockwise direction tov lower. the plow bottom and frame.

The controlling and supplying means 21 is shown in Figure 2 as embodying typical construction. in. which the working parts are contained in a suitable housing 38 which may be secured to the rear portion of the tractor body in in any appropriate manner. The housing has avertical. valve cylinder 39, within which a valve piston 48 is axially shiftable, and a fluid-supply or high-pressure passage or conduit 41 connected at one end to a suitable source of supply, such as a pump 42 (illustrated schematically in Figure' 2).

The high-pressure line 4| and pump 42 represent the high side of the. system. The low side of the system" includes a reservoir 43 to which the pump is connected as by an intake conduit 44. The reservoir 43' is connected by a return conduit 45 to an. exhaust passage 46 in the housing 38; The passage 45 includes a pair of branches 4'? and 48 connected at axially spaced points in communication with the valve cylinder 39'; The fiuid-pr ssure-transmitting conduits 2'3 and 29 are also connected to the valve cylinder 39 by means of a pair of passages or conduits 49 and '58, respectively. A spring-loaded check valve 5| controls the passage 49-28 and a similar check valve 52 controls the passage 50-29.

The valve 40' is shown in Figure 2 in its neutral positionand'both check valves 5 l. and52'. are closed; therefore, the fluid motor 26 ishydrau lically locked and the implement part I420 will be maintained in its selected position. Regulation of the control valve 40 is effected by means of a control lever 53 carried by the housing 38 on a transverse rockshaft 54' and conveniently located'with respect to the operator's station [2 (Figure 1). Within. the housing. 38, the rock'- shaft- 54 hasfl'xe'd thereto a crank arm 55' which is connected by a link 56' to the upper end of the valve 46. Rocking, of the control lever 53 in either direction" will result in axial shifting of the valve 4:: in the valve cylinder 33;

The valve 40, as illustrated, is of the spooltype and is so constructed that in its neutral position, as shown, fluid supplied'by the pum 62' through the passage 4'! will circulate axially in opposite directions from the central portion of the valve cylinder 39 to end'portions of the cylinder 39 for return through the exhaust branches 4? and 48 and thence through the exhaust passage 46 and return duct 45 to thereservoir 43. It will beunderstood', of course, that the pump 42 is operated by any suitable means on' the tractor.

For'thepurposes of effecting the desired control;of' the fluid-pressure system, the va-lve'40 includes a central" cylindrical portion 51, and upper and lower cylindrical portions 58 and 59 respectively. Intermediate the portions 51 and 58, the valve is provided with-a tapered section 68, and a similar tapered section 5| is provided intermediate the portions 5"! and 591 The-valve cylinder 39 is of substantially uniform diameter throughout its length except for annular recesses 62, 63" and 64. These-recessescorrespondingin position respectively with the high-pressure passage 4| and exhaust branches 4! and 48. In the neutral position of the valve 48, as shown in Figure 2, the tapered portions 68 and 6| are located a illustrated with respect to the check valves and 52, respectively.

Operation of the system to the extent described is as follows: The control lever 53 may be moved a maximum distance forwardly, or in a counterclockwise direction, to effect maximum upward shifting of the valve 48. The result is that the cylindrical portion 51 of the valve cuts off the supply of fluid upwardly through the valve cylinder and directs the fluid downwardly to the check valve 52. The pressure rise in this portion of the system causes the check valve 52 to open and fluid is supplied under pressure through the passage 58 to the lower conduit 29 which, in turn, supplies fluid under pressure to the closed end of the cylinder through a conduit or passage comprising communicating ducts 65, B8 and 81 (Figure 3). Ignoring for the moment the detailed structure of the cylinder 30, it will be seen that the result is to extend the piston rod 32 with respect to the cylinder and thus to raise the implement to the position shown in Figure 1.

Simultaneously with the raising of the valve 40, as aforesaid, the tapered portion 88 engages the stem of the upper check valve 5| and causes this valve to open to its maximum extent against its loading spring, thereby establishing communication between the upper conduit 28 and upper passage 48 and providing for the exhaust of fluid at its maximum rate of flow from the rod end of the cylinder past the upper portion of the valve 48 and into the exhaust branch 41 and thence through the passages 46 and 45 to the reservoir 43. Return of the control lever 52 to its neutral position effects hydraulic locking of the motor 26 as stated above.

Rocking of the lever 53 a maximum distance in a clockwise direction, or to the rear, as viewed in Figure 1, reverses the procedure just described and the motor 26 may be contracted to efiect lowering of the implement part.

The control means 21 presently illustrated includes means for controlling the volume of fluid under pressure to the motor 26 to eifect either high-speed or low-speed operation of the motor. This means includes the valve 40 and the parts just described, together with means for indicating to the operator certain positions of the valve in which the system may be caused to operate at either of the speeds referred to. For this purpose, the control lever rockshaft 54 carries fixedly thereon within the housing 38 a plate 18 which is centrally notched at H to normally receive a roller 12 which forms part of a spring-loaded arm 13 that is pivoted to an interior portion of the housing 38, as at 14. Opposite portions of the plate member that border the notch II are substantially straight but terminate in lugs 15 and 16, respectively. This arrangement provide that the operator, when moving the control lever forwardly, for example, may, at an intermediate point in the range of movement, feel first the disengagement of the roller 12 from the notch 1| and then the engagement of the roller with the lug 15. At this point, the valve 48 will be only partly shifted upwardly in the valve cylinder 39 and a smaller volume of fluid will be supplied as compared with the volume of fluid supplied when the valve 48 is fully opened, since partial shifting of the valve 48 results in only partial opening or cracking of the valve 5| thus metering. or reducing the rate of flow of, fluid exhausted from the motor through the conduit 28. Although the pressure in the system will actually open the lower valve 52 to it maximum, metering as aforesaid at the valve 5| will result in diversion of part of the fluid on the high side back to the reservoir through the pressure-relief means described below. Various types of metering valves may be used in place of the check valves 5| and 52, as in United States Patent 2,532,552, but, since the present system is shown only diagrammatically, the detailed structure has been omitted.

In the event that the operator desires to effect a relatively fine adjustment of his implement, he will utilize this slow speed. He can, of course, move the control lever past the point at which he feels engagement between the roller 12 and lug 15 to obtain high-speed operation. A similar result may be obtained by movement of the lever 53 in the opposite direction.

The control system illustrated has means for automatically returning the control valve 40 to neutral in response to excess pressure in the system. Part of this means includes an arm 11 fixed to the rockshaft 54 and associated with a bell crank having arms 18 and 19. This bell crank is pivoted at to the interior of the housing 38. The arm 18 carries a roller 8| which rides on an arcuate portion 82 of the arm 11. This portion is formed about the axis of the rockshaft 54 and terminates at its opposite ends in cut-off corners 83 and 84 respectively. .The bell crank 1819 is spring-loaded by means including a rod 85, a compression spring 86, and a washer 81. A portion of the housing 38 is bored at 88 to accommodate the spring 88. The rod 85 is connected at one, end to the arm 19 and is headed at its other end to carry the washer 81. The spring 88 is confined between the washer 81 and a wall 89 which forms the end of the bore 88. The action of the spring is such as to keep the roller 8| in constant engagement with the arcuate portion 82 or either of the corners 83 and 84, as the case may be.

The extent of the arc 82 is proportional to the range of movement of the control lever 53 in efiecting slow-speed operation of the system in either direction. Hence, when the operator releases the control lever 53 the spring-loaded lever or arm 13 will be efiective to return it to neutral from either of its slow-speed positions, inasmuch as the corners 83 and 84 on the plate 11 do not, in this range of movement of the lever 53, cooperate with the roller 8| to establish a lock on the rockshaft 54. Also, operation of the relief valve as an adjunct to metering, as stated above, will not affect the control lever, since the lever is not locked but will be held by the operator in either slow-speed position. However, when the control lever is moved to its maximum or high-speed position in either direction, the roller 8| engages with one or the other of the corners 83 or 84 and acts to hold the control lever 53 in either maximum position. The operator may, of course, overcome the locking action at will and move the control lever 53 to any intermediate position.

The housing 38 has a bore 98 below the bore 88 and both bores open to the return passage 48. A valve BI is slidable in the bore 80 and normally rests on an annular apertured wall 92 which separates the bore from a coaxial bore 93. Communication between the passage 4| and the bore 93 is controlled by a relief valve 94, normally held on a valveseat 95 by means or a relati v'ely' neavy compression spring. as. the spring; 9!? is calibiated madame-valve 94 seated during operation or the system at" normal'pressures;

m the event of abnormal ties of pressure in the system; the valve an em open against the spring 96 and fluid from tl ili'igh pr'c'ssth as: sage H will enter mature 9'32 pass through the apertured wall 92 and'raise thevalve member fil in thebore 60; upward-movement of the valve member 91 is followed by 'eng'agementof this valve member with the headed endof the rod 85; thus compressing the spring Stand rocking the bell crank 18 -4 fifin acounterclockwise direction to-release the roller 8% from one orf the-other of thec'orn'ers 83'01 84 on the plate Ff. Upon release of the roller fron'ithe plate, the spring-- loaded arm or lever 73 causes the rocksli'aft-is and plate 10 to 'move angularly until the roller '52 again seats in the" arcuate"notch 'H", which position determines the neutral position" of the valve 49'. Pressure'relief valves of thistyp'e' and for the purpose described are well known and any conventional constructionmaybe substituted for that illustrated; filirce'ss fluid pressure that causes upward movement ofthe valvemember 9i and unlocking of the" bell crank it-'59 is returned to the reservoir through the passages 45 and 46 by means of" a p'airof intersecting bores 91' and 93 in the'valverherriher' M. It will be understood, of course} thatvihen'the'valve memher 9'! raises, the bor'e 98willcommunicate with the horizontal portion of the return conduit is;

In systems of the type heretofore known, an excellent example of which is disclosed" and claimed in U. s'i i atem' 214423306, issued to McCormick, the pressure-relief 1 means is utilized in connection with adjustable stop between the piston'and piston rod'for' deliberately creating a condition in which stop" means elements may intercngage" at a? selected" point to limit travelof the pistbn'rod' with respect to the cylinder, thereby. causing the pressure reli'ef means to return thebo'ntrol v lve" tomcat-rail Such arrangement, as aforesaid; is". desirable in returning a pew; for example, to'workmg posit'ion after it has been raised. in the use" of'a system of the type referred to, the operatoris relieved of i the burden of re-d 'e'terininingi the groundworking position of his implement upon lowering of the implement from a raised position. These characteristics are, of course present in other situations, asin a harvester, for example, in connectionwith the raising and. lowering of the harvester platform; although, the operations may be in reverseorder.

One characteristic of the system described generally above is that the stops are positive; that is, onceset, the stops must be readjusted manually in-the event that the operator desires to adjust the implement to a position of increased depth, for example: beyondthatdeter'- mined: by thestops- Then, he must again read-- just the'stopsito secure-his= original adjustment, all: of which reduiresthat the operator dismount from: the tractor.

According to the present invention, there. is provided stop means: including provision where- .by thestops or their-iequivalent-maybe controlled by the operatorthrough" the medium oi the control lever 53; therefore;theioperator need-not dismount. from the tractor. At the sametime, the stop meanslis' sotarranged. as to retain the original adjustment even though allowing for variations-instills?ad jiistmentlfronntimcitb time.

The manner inwliich these desirable-results are achieved in the preferred form' of" the invention illustrated will be described below.

As previously described, the closed end of the" c'ylin'der Sll has the communicating passages '65; 66 and 61, the fluid-pressure=ti'ansmitting conduit or hose 29 being connected to the cylinder via the passage 55'. Thepassage 66- is part of a bore that. interse'ctsthe passage 65; a coaxial portion of this bore" being designated; at I90. The end of the cylinder that hasthe mountingclevis' 3 5' includes a cap it! within which a bore m2 coaxial with the bore portions-$6-and (09-. The bore 86--l0lllll2" carries slidably therein a valve member H23; This valve mem ber is reduced at N34, to establish normal com munication between the passage portions 65; 66'- and ST, and'is headed at' H35 to'effect: a bearing. in the bore I02 Yieldable means in theform" of a; coiled compression springv Hit biases the valve N33 to its normal position, as illustrated, so that fluid under pressure may be supplied through the conduit 29 or, alternatively, fluid may be exhausted from the closed end ofthe cylinder through thepassages-Gl, Stand 65 and conduit 28, depending upon which direction the piston is moved in the cylinder 38.

A transverse bore 161 intersects the bore I00 and rotatably carries an actuating member I08; This'member is cylindrical except for a notch 189 which provides aflat disposed in abutting relation with the end of the valve I613;

The rockable member mil-may be appropriate- 1y sealed at Mt in the bore I31 and includes a reduced external shank H! to which is fixed a depending actuating: arm H2. This arm is disposed at one side of the'cylinder 3i! and cooperates with an adjustable stop or limit member I 13' mounted in a bracket l M- rig-idly carried by the clevis 33 of the piston rod 32 (Figure 4). The member H3 is slida'ble through the bracket H4 but'is selectively or adjustably positionable withres'pect to the bracket by means of a threaded securing element such asa hand nut H5. Rela= V tive movement of the motorpartcomprising the piston 31- with respect to the motor part comprisirig'thecylinder 313 maybe-selectively determinedor limited by engagement of the member H3 with the lever or arm H2 onthe rockable mem-- ber IE8; and the position of engagement betweenthe members H3 and HZ-may be determined-by adjusting the member H-3- inthebracket H4; When'the piston 3lis moving toward the closed endofthe=cylinder 30, the member I it will'move toward the arm H-ii onthe actuating member Hi8; Engagement of the member 1 t3 with the arm 2- rocks the actuating member 188 in a clockwise direction, as-viewed in Figure 3, and the flat formed-- bythe notch lilil acts as a cam to displace the valve 133 against the biasing means or spring Iiltp- The valve N33- is thus caused to: close the bore tifiand discontinue communication between the passage portions 65 and 61, whereupon a condition of excess pressure is created in the system which effects operation of the pressure relief valve 94- so that: the bell crank Id-19 is rocked in: a counterclockwise direction to relieve its locking: effect on the plate H and the control valve 40 returns to neutral under the: action of the springeloaded arm 13-.

To the extent described; the present system is generally similar to that disclosed inthe patent to McCormick mentioned above; However, the improvement incorporated in the present system permits increased flexibility of thefluid-pressure 9 apparatus. To this end, the valve I03 has an axial bore H6 and a pair of transverse smaller bores or orifices II! and H8, each of which intersects or is in communication with the axial bore IIB. When thevalve I03 is in its normal position, as illustrated in Figures 3 and 4, the orifice or passage II! is within the bore 66 and the orifice or passage H8 is within the bore I00. When the valve I03 is shifted to its closed position, or upwardly in Figures 3 and 4, the orifice H8 is within the passage 65 and the orifice II! is within the passage 67. Thus, communication is established between the chamber of the cylinder 30 and the conduit 29 via the passage 61, orifice I I I, bore IIG, orifice H8 and passage portion 65.

Assuming now that the operator has moved the control lever 53 to its maximum position rearwardly to efiect high-speed lowering of the implement, fluid under pressure from the high pressure passage II in the housing 38 Will be conducted through the passage 49 and conduit 28 to the rod-end of the cylinder and fluid from the closed end of the cylinder will return to the reservoir 43. When the motor parts 30 and 3| have moved relatively to the extent determined by adjustment of the stop member I I3, the member II 3 effects actuation of the member I98 to shift the valve I03. The restriction then set up by the throttling or by-pass orifices Ill and H3 and bore I I6 is such as to prevent further operation of the system at high speed and thereupon the pressure-relief means operates to return the control valve to neutral, thus stopping relative movement between the motor parts and hydraulically locking the implement in its desired position of adjustment.

If the operator is satisfied that his selected adjustment is appropriate, he does nothing more with respect to the control lever 53 or the adjustment of the motor and continues to operate until the end of the furrow is reached or until some other condition arises which requires adjustment of the implement. The valve I03, being closed, interrupts communication between the circuit portions including the conduit 23 and the chamber in the cylinder 33, except for the restricted by-pass established by the ports or orifices H6- I I'I-I I8; and, when the operator desires to raise the implement, he moves the control lever 53 forwardly so that fluid pressure is transmitted through the conduit 29 and throttling by-pass to an extent sufficient to move the piston 3| outwardly in the cylinder so that the member II3 shortly becomes disengaged from the arm I I2 on the rotatable member I08, whereupon the spring I06 will fully open the valve I03 and continued raising of the implement may be effected.

In the event that the operator, after lowering the implement, desires to increase the working depth of the implement, he may do so, notwithstanding that the stop means has already operated to return the control valve II] to neutral, by moving the control lever 53 rearwardly to its slow-speed position, for example, which position he can determine by feeling initial engagement of the roller I2 with the lug I6 on the plate 10. Or, he may move the lever fully to its high-speed position and hold it there against its tendency to return to neutral because of the excess pressure condition created by the throttling at I I6-I I I- II8. In the first case, a smaller rate of flow is permitted by the partial opening of the check valves and 52, and in the second'case the maxi tem. In either case, the system will operate at slow speed, and the piston 3| is capable of forcing fluid through the throttling by-pass in the valve I 03. It will be seen from Figure 3 that engagement of the end of the member I I3 with the arm II2 eifects clockwise angular movement of the arm, whereby the member I I3 may ultimately pass under the arm so that further movement of the piston 3| toward the end 35 of the cylinder may be had. Thus, th operator may obtain adjustment beyond that normally determined :by the stop means. Such temporarily selected adjustment does not affect the setting of the stop means and thereafter he may operat the system to secure lowering of the implement to the uniform depth originally selected.

The valve I93 and associated stop means may be repositioned to obtain the same result in connection with extension of the fluid motor for use with other implements, as a harvestenfor example. In either case, the most desirable application of the invention is in connection with a system in which the control valve is automatically returned to neutral. However, the valve may be applied to other systems. If used in a system without an automatic return for the control valve, for example, the operator will realize that a condition of abnormal pressure exists and he himself will return the control valve to neutral, since in most systems having pressure-relief valves, there is an audible chattering of the valve which serves as a signal to the operator.

Other objects and features of the invention not specifically enumerated above will undoubtedly occur to those versed in the art, as will numerous modifications and alterations in the preferred construction illustrated, all of which may be achieved without departing from the spirit and scope of the invention as defined in the appended claims.

mum pressure allowed by the relief valve will still "be available in the high-pressure side of the sys- What is claimed is: 1. For an implement of the type including a supporting part and an implement part connected thereto for movement with respect thereto in at least one direction: fluid pressure apparatus comprising a fluid motor having first and second parts connectible respectively to the implement and supporting parts and arranged for movement of one relative to the other in at least one direction to move the implement part as aforesaid; a source of fluid pressure; a fluid-pressure circuit interconnecting and including said source and the motor for the transmission of fluid between the motor and said source; a selectively positionable control valve in the circuit having a neutral position to render the circuit ineffective for the transmission of fluid between the source and the motor, and further having highand low-speed positions for selectively effecting the transmission of fluid respectively at relatively high or low rates of flow between the source and the motor for selectively effecting relative highor low-speed movement of one motor part with respect to the other in said direction; means including a second valve in the circuit actuatable from a first position, in which adjoining portions of the circuit are relatively freely in communication so that the circuit is effective to transmit fluid at said relatively high rate when the control valve is in its high-speed position, to a second position in which communication between said adjoining circuit portions is restricted to such an extent that the circuit is incapable of transmitting fluid at said high rate; actuating means operative in response to a predetermined extent of high-speed movement of (said one motor part relative to said other partin the aforesaid direction'for actuatingsaid second valve to its second position and henceato interruptsaid high-speed movement; means operative inresponse to said interruption of movement for returning the control valve to its neutral position;

:means operative in respons to thecondition including actuation of said second valve to its-second position for establishing between said adjoining circuit portions a communicationrendering said circuit capable of carrying fluid 'at -said relatively low rate when the control valve is moved to its low-speed position, so thatrelative movement of the-aforesaid parts may be continued in said direction at said relatively low,

speed; and said actuating means including cooperating elements having provision for overrunning after actuation of the second valve meansto its second position so that continued low-speed operation of the motor may "he'had without afiecting said second valve.

2. For animplement having a supportingpart and a movable part connected to the supporting part for "movement with respect to the latterin apredetermined range in one direction'and-for return movement in another direction, thecombination of two-way fluid-pressure means connectible between'said parts and including control means for regulating the fluid-pressure means to hold said parts against relative movementaand selectively operative to move said movable part in either direction at either a high ora'low rate of speed; limit means, connected between the fluid-pressuremeans and one-oisaid parts and operative-in response to movement of saidmovable part in one direction at high speed to a predetermined point in its range, foractuating the control means tocondition the fluid-pressure means for holding said movable part ,againstlrurther movement in either direction; and means connected to said limit means-and to the fluidpressuremeans and operativein responseto the aforesaid operationof said limit means to condition thefiuid-pressure means ioriurther operation atvgnly said low rate of speed either to movesaid second part insaid direction beyond said predetermined point or to returnrsaid part in said other direction.

3. For an implement .of .the type including a supporting part and an implement part connected thereto for movement with respect ithereto inat least one direction: fluid-pressure,apparatuscomprising a fluid motor having firstandsecond parts provided with means for connection respectively to the implement and supporting parts andarrangedfor movement ofone relative to the other in at least one direction to move the .iimplement part as aforesaid; a source of fiuidpressurehaving high and low sides; a fluid-pressure circuit connected to and including the fluid-pressure source. and the motor for transmitting'fiuid pressure between the motor and the source; a control valve in the circuit selectively movable toia neutral position to cut out the circuit between the source and the motor or to an active position for establishing the circuit; pressure-responsive means in the circuit operative .in response tooabnormal fluid pressure in the circuit for diverting the fluid pressure to the low vside of the fluidpressure source; means connected between the pressure-responsive,means and the control valve for returning the control valve from its active position to its neutral position in response to actuation of said pressure-responsive means; means in the circuit including a second valve and :a -.restricted passage controlled day said second valve, said-seeondwalveibeing actuatable from a first positienopeningthe .circuitifor the :supply of fluid to the motor :at normal pressures, -.to a

second position closing said circuit except for .fiuid-pmssnrei transmission? through said restrict- ,ed passage sozastocause anzabnormality of pressure in said circuit ,effectivevto operate the pressure+responsiv e '7 111693118, actuating 1 11183118 operative .in :response to a predetermined extent of movement of onelmotor part relative to the other insa-id direction vaforractuatingthe second valve means from its first position to its second positionand hence to efiect return of the control valve to neutral i-v-iaoperation of .said pressure-responsive means; aandsaidx-actuating means including cooperative elements ha-ving :provision for overrunning relative to the-second valveimeans after actuation of said second valve-means to-itssecand position l so that=said second valve'means is 'unaiiected by subsequentzre-positioningof the control 1 valve toward its active position 'to effect iiuid transmission through rsaid tcircuit via :said restricted passage tier subsequent operation 10f the motor ata slower speed.

4. For an implement of the type including a supportingpart. and animplement part connected thereto for movement with respect thereto in at least onedirection: fluid pressure apparatus comprising: a fluid-motor ihavingfirst: and second parts provided with zmeans for connection respectively to the implement: and supporting parts and:arranged for-movement of one wrelative to the other in :at iea-stmne direction :to move the implement part was -;afor,esaid; a source of fluid pressure having high and loW;sides;;afiuid-pressure circuit:conneeted=to-and including the fluidpressure source *and {the motor i or transmitting fluid pressure between-itheimotoriand the source; a control w-valve in the-circuit--selectivelvmovable to a neutral position ,tozcutout ithe'circuit between the source and ;the imotorior to an active position ZfOI' establishing the circuit; pressureresponsive means in the -circuitoperative in vresponse to :abnormal fluid -.pressure in the circuit for diverting the fluid pressure 'to the lowside of the fluid-pressure source; ,means connected between the pressure-responsive means and the control valveforreturning-the control valve from its active position to its neutral position in response to actuation of said "pressureqresponsive means; means including 7 a second valve in :the circuit actuatable ifromza @first position conditioningthe circuit forthe'supplyof flu-idto the motor at normal-pressures; to a second position'restricting 'said circuit to an extent :suffic-ient to cause an abnormality of =pressu-retherein effective to operate thepressure-eresponsiveameans; actuating means operative .in FTBSPOHSB -.to a predetermined extentoflmovementof one motor part relative'to the other-in said dimctionioriactuating the second valve meansirom .its Jirstposition toitsisec- 7 l3 restricted passage; and said actuating means including cooperative elements having provision for overrunning relative to the second valve means after actuation of said second valve means to its second position so that said second valve means is unaffected by subsequent operation of the motor in said direction and at said slower speed.

5. A hydraulic motor assembly comprising: a first motor member including an interior cylinder chamber and first and second opposite ends, said first end having a central piston rod opening therethrough; a second motor member including a piston withinthe cylinder chamber having a piston rod extending outwardly through said opening; means on the first motor member including a fluid passage communicating with the cylinder chamber at the first-end side of the pie-- ton; second means on the first motor member providing a fluid passage communicating with the cylinder chamber atthe second-end side of the piston, and including a first bore at said second end of the cylinder chamber disposed generally lengthwise as respects the cylinder chamber axis and a second bore transverse to and intersecting the first bore; valve means confined to said second end of the cylinder chamber and including a valve seat in said first bore, a valve shiftable in said first bore selectively between two positions for seating on or unseating from said valve seat, and a restricted fluid passage by-passing the valve seat and communicating said first bore and the cylinder chamber at the second-end side of the piston; spring means biasing the valve to one of its positions; a rockshaft in the second bore having an end portion proximate to the valve and provided with cam means engageable with said valve to effect shifting thereof, and having an opposite end portion external to the cylinder chamber and provided with an operating arm for efiecting rocking of said rockshaft; and control means operative between the rockshaft-operating arm and the piston rod, including an elongated control element outside the cylinder chamber and shiftable lengthwise thereof and having a first end portion proximate to the first end of the 4 cylinder chamber and a second end proximate to the second end of the cylinder chamber and engageable with the rockshaft-operating arm, and means engageable between said first end of the control element and the piston rod including an operating element on a part of the piston rod external to the cylinder chamber and so arranged that movement of the piston and rod toward the second end of the cylinder chamber effects movement of the control element in the same direction for efiecting seating of the valve and establishing effectiveness of said by-pass passage, said control means including provision in one of its elements for lengthwise shifting of said one element relative to the rockshaft-operating arm to accommodate further movement of the piston and piston rod in the aforesaid direction after said valve is seated and fiuid is transmitted through said by-pass passage.

6. A hydraulic motor assembly comprising: a cylinder having first and second opposite ends, said first end having a central piston rod opening therethrough; a piston within the cylinder having a piston rod extending outwardly through said opening; means on the cylinder including a fiuid passage communicating with the cylinder at the first-end side of the piston; second means on the cylinder providing a fiuid passage communicating with the cylinder at the second-end side of the piston, and including a first bore at said second end of the cylinder; valve means confined to said second end of the cylinder and including a valve seat in said first bore, a valve shiftable in said first bore selectively between two positions for seating on or unseating from said valve seat, and a restricted fluid passage by-passing the valve seat and communicating" said first bore and the cylinder at the secondend side of 'the piston; spring means biasing the valve to one of its positions; a rockshaftjournaled on the cylinder and having cam means proximate to'and engageable with said valve to effect shifting thereof, and having an operating arm relatively remote from said valve for eifecting rocking of said rockshaft; and control means operative between the rockshaft-operating arm and the piston rod, including an elongated control element shiftable lengthwise or the cylinder and having a first-end portion proximate to the first end of the cylinder and a second end proximate to the second end of the cylinder and engageable with the rockshaftoperating arm, and means engageable between said first end of the control element and the-piston rod including an operating element on the piston rod and so arranged that lengthwise movement of the piston and rod in one direction effects lengthwise movement of the control element for effecting seating'of the valve and establishing effectiveness of said by-pass passage, said control means including provision in one of its elements for lengthwise shifting of said one element relative to the rockshaft-operating arm to accommodate further movement of the piston and piston rod in the aforesaid'direction after said valve is seated and fluid is transmitted through said by-pass passage.

7. A hydraulic motor assembly comprising: a cylinder having first and second opposite ends, said first end having a central piston rod opening therethrough; a piston within the cylinder having a piston rod extending outwardly through said opening; means on the cylinder including a fluid passage communicating with the cylinder at the first-end side of the piston; second means on the cylinder providing at fluid passage communicating with the cylinder at the second-end side of the piston, and including a first bore at said second end of the cylinder; valve means confined to said second end of the cylinder and including a valve seat in said first bore, a valve shiftable in said first bore selectively between two positions for seating on or unseating from said valve seat, and a restricted fluid passage by-passing the valve seat and communicating said first bore and the cylinder at the second-end side of the piston; means biasing the valve to one of its positions; and control means operative between the valve and the piston rod, including an elongated control element shiftable lengthwise of the cylinder and having a first-end portion proximate to the first end of the cylinder and a second end proximate to the second end of the cylinder and including a valve-engaging element, and means engageable between said first end of the control element and the piston rod including an operating element on the piston rod and so arranged that lengthwise movement of the piston and rod in one direction efiects lengthwise movement of the control element for effecting seating of the valve and establishing effectiveness of said by-pass passage, said control means including provision in one of its elements for lengthwise shifting of said one element relative to the valve to accommodate further movement of the piston and piston rod in the aforesaid direction after gamma 15 said valve is seated and .fluid transmitted through said -by-pass passage.

8. A hydraulic .motorassembly comprising: a cylinder having first and second opposite ends, said first end having ,atcentralpiston rod opening therethrough; a'piston within the cylinder having ;a piston rod extending outwardly through said opening; means on the cylinder including .a fluid passage communicating with the cylinder at the-first-end side of the piston; second means on the cylinder providing a fluid Passage communicating with the cylinder at the second-end side of the piston,rand including a first bore at said second end of the cylinder; valve means confined to said secondend of thecylinder; and including a valve seatin said first bore, a valve shiftable in said firstboreselectivelybetweentwo positions for seating on-or unseating from said valve seat, rand a throttlingfluid passage through said valve for by-passing the valve seat "when the valve is seated; means biasing the vaive to its unseated position; and control means operative between the valve-and the piston rod, including an elongated-control 'element-shiftable lengthwise of the cylinder and having a first-end portion proxizmaterto the first-endsof the cylinder and-asecond end proximate to the-second'end-of the cylinder :and including :a valve-engaging element, and :means .engageable between-said first end of the control element .andthe piston rod including an operating .element on the piston rod and so arranged that lengthwise movement of the piston and rod ,inone direction .efiectslengthwisemovement ofthe control element for efiecting seating of the valve and establishing efiectiveness of said by-pass passage, said control means including provision in one of its elements for lengthwiseshifting ofsaid-one element relative to the valve to accommodate further movement of the pistonand piston rod in the aforesaid direction after said valveis seated and fluid is transmitted through; said by-pass :passage.

.EMIL F. JIRSA.

References Cited .in the .file of this vpatent UNITED STATES PATENTS Number Name Date 917,642 McEiroy Apr. '6', 1909 2,223,792 Muir Dec. 3, 1940 2,243,364 Trautman May 27, 1941 2,335,809 Stacy Nov. 30, 1943 2,383,689 Silver Aug. 28, 1945 2,444,228 Huthsing June 29, 1948 FOREIGN PATENTS Number Country Date 527,171 Great "Britain Oct. "3, 1940 

